1. Field of the Invention
The present invention relates to a medium for cultivating tumor cells, comprising the following constituents: (a) fetal calf serum (FCS), (b) penicillin-streptomycin, (c) L-glutamine, (d) transferrin, (e) insulin, (f) human epidermal growth factor (EGF) and (g) α-transforming growth factor (α-TGF). Furthermore, the present invention relates to a method for characterizing tumor cells or potential tumor cells, respectively, comprising the culturing of cells in the inventive medium, and the two tumor cell lines LNHOS1 and PTHOS1 established by means of the inventive culturing method.
2. Description of Related Art
Due to the use of immunohistochemical and molecularbiological examination techniques it has become possible to identify epithelial tumor cells in lymph nodes (Byrne et al., J. Surg. Oncol. 13 (1987), 409–411; Calaluce et al., J.Surg.Oncol. 67 (1998), 194–202; Latza et al., J.Clin.Pathol. 43 (1990), 213–219; Liefers et al., NEJM 339 (1998), 223–228; Pantel et al., Prog.Histochem.Cytochem. 30 (1996), 1–60; Passlick et al., J. Clin. Oncol. 12 (1994), 1827–1832; Raymond et al., Pathology 21 (1989), 11–50; and Sidransky, Science 278 (1997), 1054–1059). However, despite a growing number of publications which were able to prove a prognostic relevance of nodal early disseminated tumor cells in patients with carcinomas of the lungs, breasts, prostrate and the gastrointestinal tract (Izbicki et al., NEJM 337 (1997), 1188–1194; Hosch et al., Pancreas 15 (1997), 154–159; Passlick et al., J.Clin.Oncol. 12 (1994), 1827–1832; Greenson et al., Cancer 73 (1994), 563–569; and Liefers et al., NEJM 339 (1998), 223–228), the biological relevance of immunohistochemically detectable individual tumor cells remains unclear. This is due to the fact that so far it is almost impossible to further characterize these cells due to their extremely low frequency (1 tumor cell against the background of 104–105 normal lymph node cells). The uncertainty accompanying previous examination methods whether individual tumor cells are tumorigenic micrometastases or merely scaled-off and avital cells of the primary tumor presently prevents the introduction of this parameter into the international “tumor staging” nomenclature, i.e., it also does not permit making any prognoses or taking therapeutic measures which may be necessary.
Thus it is the underlying object of the present invention to solve the technical problem of overcoming these drawbacks of the methods used in the prior art, i.e., to provide means which allow identification whether the potential tumor cells in a tissue sample represent viable and malign tumor cells.